Add additional check for assignment instead of equation

Author: Datseris

CHANGELOG.md

@@ -3,6 +3,11 @@
 ProcessBasedModelling.jl follows semver 2.0.
 Changelog is kept with respect to v1 release.
 
+## 1.7
+
+- Added an additional check when constructing the raw equations that catches
+  errors of typing `x = expression` instead of `x ~ expression` as a process.
+
 ## 1.6
 
 - Added an additional step when constructing the raw equation vector to be passed into an MTK model. In this step it is also checked that the RHS for all equations is an `Expression`. Sometimes it is easy to get confused and mess up and make it be an `Equation` (i.e., assigning the LHS-variable twice). This now will give an informative error.

Project.toml

@@ -1,7 +1,7 @@
 name = "ProcessBasedModelling"
 uuid = "ca969041-2cf3-4b10-bc21-86f4417093eb"
 authors = ["Datseris <[email protected]>"]
-version = "1.6.0"
+version = "1.7.0"
 
 [deps]
 ModelingToolkit = "961ee093-0014-501f-94e3-6117800e7a78"

src/make.jl

@@ -14,6 +14,8 @@ During construction, the following automations improve user experience:
   a [`ParameterProcess`](@ref) is created for said variable(s) and a warning is thrown.
 - Else, an informative error is thrown.
 - An error is also thrown if any variable has two or more processes assigned to it.
+- An error is thrown if any of the given processes are not actually processes,
+  but rather expressions without a LHF-variable.
 
 `processes` is a `Vector` whose elements can be:
 
@@ -161,7 +163,9 @@ end
 
 function check_rhs_validity(processes)
     for p in processes
-        if rhs(p) isa Equation
+        if !(typeof(p) <: Union{Process, Equation})
+            throw(ArgumentError("Process $(p) is not actually a process!"))
+        elseif rhs(p) isa Equation
             lvar = lhs_variable(p)
             throw(ArgumentError("Process assigned to variable $(lvar) is ill defined. "*
                 "The RHS is an `<: Equation` type but it shouldn't be."

test/runtests.jl

@@ -238,6 +238,16 @@ end
     @test_throws ["an `<: Equation` type"] processes_to_mtkeqs(procs)
 end
 
+@testset "not actual process" begin
+    @variables z(t) = 0.0
+    @variables x(t) = 0.0
+    procs = [
+        ExpRelaxation(x, x^2, 1.0),
+        -x,                    # is an equation, not a process!
+    ]
+    @test_throws ["not actually"] processes_to_mtkeqs(procs)
+end
+
 @testset "registering default" begin
     using .TestDefault
     @variables z(t) = 0.1